It looks increasingly likely that no presidential candidate will arrive at the Republican convention in July with a majority of delegates. Donald Trump still has a very plausible path to a majority, but it depends on winning most, if not all, of the states in contention on March 15, and then dominating the remainder of the Northeast and Mid-Atlantic states. This is because Trump's weakest region is the West, and if at least some of the non-Trump candidates are still around, he could well lose winner-take-all California, South Dakota and Montana, as well as proportional contests in states like Utah, Washington, New Mexico, and Oregon. So there still is a real chance to deny Trump the delegate majority he needs to claim the nomination by right.

But that doesn't mean it'll be easy to deny Trump a plurality.

As we saw on Tuesday, Trump can continue to win contests in states like Michigan with under 40 percent of the vote so long as the other candidates retain their own constituencies. This was true when Trump faced a multitude of opponents. But it remains true as the field has narrowed, because Ted Cruz, another anti-establishment figure, remains Trump's strongest opposition, leaving the establishment-friendly candidates with only a minority of the primary electorate to consolidate.

And if Trump comes into the convention with a plurality of the delegates, denying him the nomination will require changing the rules. Under the rules adopted for the 2012 convention, only candidates with a majority of the delegates from at least eight states can have their names placed in nomination:

(b) Each candidate for nomination for president of the United States and vice president of the United States shall demonstrate the support of a majority of the delegates from each of eight or more states, severally, prior to the presentation of the name of that candidate for nomination.

And, based on how those rules were interpreted in 2012, only delegates for those candidates will have their votes counted:

(d) When at the close of a roll call any candidate for nomination for president of the United States or vice president of the United States has received a majority of the votes entitled to be cast in the convention, the chairman of the convention shall announce the votes for each candidate whose name was presented in accordance with the provisions of paragraph (b) of this rule. Before the convention adjourns sine die, the chairman of the convention shall declare the candidate nominated by the Republican Party for president of the United States and vice president of the United States. [Emphasis mine.]

The last point is important, because it would imply that a candidate with a plurality of delegates could win a majority of actual votes.

If Donald Trump comes into Cleveland with a plurality, then it's likely that only he and Ted Cruz will have won majorities in at least eight states. So far, Trump has won delegate majorities in seven states — South Carolina, Alabama, Georgia, Massachusetts, Tennessee, Hawaii, and Mississippi. Cruz has four — Texas, Kansas, Maine and Idaho.

Kasich, of course, has none, and Rubio has a majority from no states but does have Puerto Rico. The remaining 14 states likely to give a majority to one candidate are: Illinois, California, Wisconsin, Maryland, Pennsylvania, Indiana, Florida, Ohio, Arizona, Nebraska, Missouri, Montana, New Jersey, and South Dakota. Neither Kasich nor Rubio is likely to win any of the latter six states. Rubio is also not going to win Ohio, and Kasich is not going to win Florida. That means that one of them either has to win a majority in each of the first six states on the above list, or get to eight through majorities in far-flung territories like the Northern Marianas. That's a tall order.

So, if the party operates under the 2012 rules, there's a real likelihood that only Trump and Cruz get their names placed in nomination, and only Trump and Cruz delegates get to vote. If that happens, whichever of those two has more delegates will win a majority of the delegates entitled to vote, and will then press the case that, under the rules, he is the rightful nominee.

Ironically, it's the insurgent candidates, the ones trying to overthrow the party leadership, who are in the best position to benefit from the rules the party adopted to quash insurgent candidates at the convention.

Now, given that the party doesn't want either to be the nominee, and given that the party makes the rules, and so can readily change them, it seems unlikely that this scenario will play out. Moreover, the 2012 rules are distinctly undemocratic and abusive, and reform is very much in order. But the problem, as so often for the Republican Party in this election season, is that it's not only Trump who has an incentive to cry foul if they do so.

Because while Trump is more likely to get the nomination under the 2012 rules than under the more transparent, fair, and democratic process that obtained prior to 2012, so is Cruz. It's possible that when the party meets in April — the most likely time a rule change would be enacted — Cruz may still have a plausible shot at overtaking Trump for a plurality, and be far more likely to have "gotten to eight" than his other non-Trump opponents.

Moreover, because voting will not be finished when the party meets, changes to the rules could affect subsequent voting. Even if the party changes the rules to make them fairer and more open, as they should, both the Trump and Cruz campaigns would have every reason to decry changing the rules in the middle of the contest, and thereby rally their supporters in the remaining contests. What odds would you give on anyone but Trump or Cruz winning California under such conditions?

The party may try to change the rules to give its preferred candidates their deserved voice at the convention, and discover that they've only made their least-preferred candidates' voices that much louder.

The bottom line: It will take an extraordinary turn of events for Trump and Cruz not to come into the convention with a substantial majority of delegates between them. Mucking about with the rules in order to increase the likelihood of a brokered convention would also be expected to increase their joint delegate total. And then, if a brokered convention does happen, the party will no longer have the option of defeating Trump and Cruz.